Thermostatically controlled pump



Jan. 11, 1966 J. P. STEFAN 3,228,380

THERMOSTAT I (SALLY CONTROLLED PUMP Filed Nov. 13, 1964 2 Sheets-Sheet 2FIG.2

JOHN P. STEFAN INVENTOR A 7' TORNEYS United States Patent O 3,228,380THERMOSTATICALLY CONTROLLED PUMP John P. Stefan, Birmingham, Mich.,assignor to Ford Motor Company, Dearborn, Mich, a corporation ofDelaware Filed Nov. 13, 1964, Ser. No. 411,016 20 Claims. (Cl. 12341.02)

This invention relates to a thermostatically controlled fluidcirculating device and more particularly to a thermostaticallycontrolled coolant pump or an internal combustion engine.

In many instances it is necessary to circulate a fluid by means of apump or other fluid circulating device that is responsive totemperature. The pump or fluid circulating device may operate inresponse to the temperature of the fluid circulated or to some othertemperature. It heretofore has been the practice to employ some elementthat has thermal characteristics for controlling the operation of thefluid circulating device. Bimetallic springs, metals having highcoeflicients of thermal expansion and wax pellets are well known formsof thermally responsive elements that are used for this purpose. Whenthermally responsive elements of this type are used, they must be inthermal contact with the part whose temperature is being sensed.Frequently, spacial limitations and other factors make this thermalcontact either impossible 'or difficult.

It is a principal object of this invention to provide a fluidcirculating device that is temperature responsive without requiring theuse of an element having thermally responsive properties.

In liquid cooled internal combustion engines it is the general practiceto provide a coolant pump for circulating the liquid coolant throughoutthe cooling jacket of the engine and through a radiator that dissipatesthe heat generated by the engine. The coolant pump must have suflicientsize to meet the maximum cooling requirements of the engine. If the pumpis designed to meet the maximum cooling requirements of the engine, itwill require significant power to operate the pump at partial and fullloads. The coolant pump, therefor, may consume considerable power forits operation during times when its full capacity is not needed.

It is a further object of this invention to provide a temperatureresponsive cooling pump for an internal combustion engine.

A temperature responsive means for actuating a fluid pump embodying thisinvention comprises a venturi section. Means is provided to circulate afluid through the venturi section. The fluid circulated through theventuri section is adapted to vaporize at the throat of the venturisection at a predetermined temperature. A device is provided to generatea signal when the fluid vaporizes within the throat and means areprovided to drive the pump in response to the signal of the device.

A coolant pump for an internal combustion engine embodying thisinvention comprises a first engine driven coolant pump that circulatescoolant through the cooling jacket and radiator of the engine at alltimes. A second coolant pump is provided. A thermally responsive deviceis provided for actuating and driving the second coolant pump from theengine only at times when the coolant temperature exceeds apredetermined temperature. In a preferred embodiment of the invention,the temperature sensing device for actuating the second coolant pump maybe of the type described in the preceding paragraph.

Further objects and advantages of this invention will become moreapparent as this description proceeds, particularly when considered inconjunction with the accompanying drawings, wherein:

FIGURE 1 is a partial perspective view, with portions broken away, of aliquid cooled internal combustion engine embodying this invention.

FIGURE 2 is a cross-sectional view taken substantially along the centerline of the coolant pump shown in FIGURE 1.

Referring now in detail to the drawings and in particular to FIGURE 1, aliquid cooled internal combustion engine is indicated generally by thereference numeral 11. The cylinder block and cylinder heads of theengine 11 are provided with a cooling jacket through which a liquidcoolant is circulated by means of a coolant pump, indicated generally bythe reference numeral 12 and shown in more detail in FIGURE 2. Theactual construction of the cooling jacket per se does not form a part ofthis invention and will not be described in detail. The heat generatedby the operation of the engine is dissipated to the atmosphere from across flow radiator, indicated generally by the reference numeral 13.The radiator 13 has a core 14 and header tanks 15 and 16 positioned ateach side of the core 14.

The coolant pump 12 has an outer housing 17 that terminates in each sidein branch arms 18 and 19 that are affixed to the front of the engine 11.The branch arms provide coolant outlets for delivering coolant to thecooling jacket of the engine 11 from the coolant pump 12. The outerhousing 17 also has an inlet fitting 21 that is formed with a coolantinlet passage. The inlet fitting 21 is connected to one end of aflexible hose 22 which is connected, in turn, to the lower end of theradiator header tank 16 so that coolant which has passed through theradiator 13 may be received by the coolant pump 12.

After the coolant has been circulated through the cooling jacket of theengine, it may be discharged through an outlet fitting 23 that issupported at the front of the engine. The outlet fitting 23 is incommunication with the lower side of an expansion tank 24. A flexiblehose 25 interconnects the expansion tank 24 with the upper end of theheader tank 15. A filler cap 26 is provided at the top of the expansiontank 24 to permit the cooling system to he filled. A thermostatic valve(not shown) may be provided in the outlet fitting 23 or at any othersuitable location for controlling the flow of coolant through theradiator 13 in response to the coolant temperature.

A driving shaft 27 for the coolant pump 12 is journaled in the front ofthe housing 17 by bearings 28 (FIGURE 2). A pulley 29 is afiixed to theforward end of the driving shaft 27 and a pulley 31 is atlixed to theforward end of the engine crankshaft 32. A belt 33 is provided totransmit rotary motion from the crankshaft pulley 31 to the water pumppulley 29.

Referring now in detail to FIGURE 2, the water pump housing 17 forms aforward, annular coolant inlet cavity 34 that is interconnected with arearward pumping cavity 35. The pumping cavity 35 is enclosed by a coverplate 36 that is affixed to the housing 17 by a plurality of bolts 37.An inner impeller 38 is afiixed to the inner end of the driving shaft27, as by a key 39. A seal 41 is positioned around the periphery of thedriving shaft 27 at one side of the inlet cavity 34 to preclude theleakage of coolant from the coolant pump 12. An outer impeller 42 has apilot portion 43 that is journaled within a bore 44 of the innerimpeller 38. The impellers 38 and 42 are coaxially disposed and axiallyaligned within the pump cavity 35.

When one or both of the impellers 38 and 42 are being driven by rotationof the engine crankshaft 32, coolant will be discharged through thebranch arms 18 and 19 into the engine cooling jacket. If thethermostatic valve is open, the coolant will be discharged from theengine .9 cooling jacket into the radiator 13 and returned to the inletside of the coolant pump 12 through the inlet fitting 21. If thethermostatic valve is closed, coolant will still be circulated throughthe cooling jacket of the engine. In this instance the coolant isreturned to the inlet side of the coolant pump 12 from a bypass outlet45 formed at the front of the engine 11. The bypass outlet 45 is axiallyaligned with a venturi section 46 that is formed within a tube that isfixed within a bore 47 formed in the coolant pump housing 17. The bore47 opens into the inlet cavity 34. A flexible hose 48 interconnects theventuri section 46 with the bypass outlet 45.

It should be apparent that the inner impeller 38 will be drivencontinuously when the engine is operating. The outer impeller 42,because it is journaled relative to the inner impeller 38 and thedriving shaft 27, will idle and not circulate coolant under normalconditions. The inner impeller 38 is made of suflicient size so that itwill satisfy the normal cooling requirements of the engine 11. In theevent that an abnormal cooling load is encountered, driving means areprovided for actuating the outer impeller 42 so that it will rotate inunison with the inner impeller 38. The driving means includes athermally responsive clutch, now to be described.

A frictional clutch surface 49 is affixed to the rear face of the innerimpeller 38 adjacent to a corresponding clutch surface 51 of the outerimpeller 42. Normally there will be a small axial gap between the clutchfaces 49 and 51. The pilot portion 43 may slide axially within the bore44 so that the clutch surfaces 49 and 51 may move into and out ofengagement. A diaphragm 52 extends across the rear face of the pumpingcavity 35 to define a pressure chamber 53 between the rear surface ofthe diaphragm 52 and the front surface of the cover plate 36. Thediaphragm 52 has a substantially rigid disc 54 aflixed at its centerupon the axis of the impellers 38 and 42. A steel ball 55 is received ina socket 56 formed in the rear face of the outer impeller 42 and asocket 57 formed in the front face of the disc 54. A Belleville spring58 engages the cover 36 and the plate 54 to exert an axial force in aforward direction upon the outer impeller 42 through the ball 55. Thisforce tends to cause the clutch faces 49 and 51 to move into engagement.

The pressure within the chamber 53 is varied in response to a change inthe temperature of the engine coolant so that the engagement of theclutch faces 49 and 51 will be dependent upon the coolant temperature.This is accomplished by providing a fitting 59 at the center of thecover plate 36 that permits fluid communication between the cavity 53and the venturi section 46 at its throat 61. A flexible hose 62 extendsfrom the fitting 59 to a nipple 63 formed integrally with the venturisection 46. A fluid passage 64 extends through the nipple 63 andterminates at the venturi section throat 61.

The temperature responsive coolant pump operates in the followingmanner. When the engine is operating and the coolant temperature is low,the rotating driving shaft 27 will cause the impeller 38 to rotate andcirculate coolant through the cooling jacket of the engine 11. Thecoolant that is returned to the inlet side of the coolant pump throughthe venturi section 46 will flow at a relatively high velocity throughthe throat 61. This high velocity flow will cause a decreased pressureat the throat 61 which is transmitted through the passage 64, hose 62and fitting 59 to the chamber 53. The resulting pressure differential onthe opposite sides of the diaphragm 52 overcomes the force in theBelleville spring 58 and permits the clutch faces 49 and 51 to separateaxially. The outer impeller 42 will then idle with respect to the innerimpeller 38.

\ As the coolant temperature rises, it will eventually reach a point atwhich it will vaporize or cavitate at the throat 61. When the coolantturns to a vapor at the throat 61, the pressure will increase or thevacuum will decrease.

The decreased vacuum that is transmitted to the cavity 53 will no longerbe sufficient to overcome the action of the Belleville spring 58 and anaxial pressure will be exerted upon the outer impeller 42 through theball 55. This axial pressure will cause the clutch faces 49 and 51 tomove into engagement and the impellers 38 and 42 will rotate in unison.When the impellers 38 and 42 rotate in unison the capacity of thecoolant pump 12 increases and additional coolant will be circulatedthrough the cooling jacket of the engine 11 and through the radiator 13if the thermostatic valve is open,

The increased flow of coolant will continue until its temperature fallsbelow the point at which it will vaporize at the throat 61 of theventuri section 46. When this occurs, the clutch again will becomedisengaged and only the inner impeller 38 will circulate coolant.

Although it is desirable to operate the engine 11 at as high atemperature as practical, its operating temperature will depend upon theboiling point of the liquid coolant that is used. In a like manner, thetemperature at which it is desirable to drive the outer impeller 42 willdepend upon the boiling point. It should be apparent that the actualtemperature at which the clutch faces 49 and 51 are engaged will dependupon the characteristics of the venturi section 41 and thecharacteristics of the fluid coolant. If the venturi section 46 isdesigned for a given coolant and a coolant having a higher or lowerboiling point is substituted, the thermal operation of the outerimpeller 42 will automatically compensate for the change in the coolantboiling point. If a coolant having a lower boiling point is used, itwill flash sooner at the venturi throat 61 causing the outer impeller 42to commence to be driven at a lower temperature. In a like manner, if acoolant having a higher boiling point is used, it will flash later atthe throat 61 and the outer impeller 42 will commence to be driven at ahigher temperature.

It is to be understood that this invention is not limited to the exactconstruction shown and described, but that various changes andmodifications may be made without departing from the spirit and scope ofthe invention, as defined by the appended claims.

Iclaim:

1. Temperature responsive means for actuating a fluid circulating meanscomprising a venturi section, means for circulating a fluid through saidventuri section, the fluid circulated through said venturi sect-ionbeing adapted to vaporize at the throat of said venturi section at apredetermined temperature, means for generating a signal when the fluidvaporizes within said throat, and means for driving said fluidcirculating means in response to the signal of said last-named means.

2. A fluid system comprising a first fluid circulating means adapted tocirculate a fluid in response to temperature variations and means foractuating said first fluid circulating means comprising a venturisection, a second fluid circulating means for circulating a fluidthrough said venturi section, the fluid circulated through said venturisection being adapted to vaporize at the throat of said venturi sectionat a predetermined temperature, means for generating a signal when thefluid vaporizes within said throat, and means for driving said firstfluid circulating means in response to the signal of said last-namedmeans.

3. Temperature responsive means for actuating a fluid circulating meanscomprising a venturi section, means for circulating a fluid through saidventuri section, the fluid cinculated through said venturi section beingadapted to vaporize at the throat of said venturi section at a predetermined temperature, means for sensing the pressure at said throatfor generating a signal when the fluid vaporizes within said throat, andmeans including pressure responsive means for driving said fluidcirculating means in response to the signal of said last-named means.

4. A fluid circulating system. comprising first fluid circulating meansadapted to be operated in response to temperature variations and meansfor actuating said first fluid circulating means comprising a venturisection, a second fluid circulating means for circulating a fluidthrough said venturi section, the fluid circulated through said venturisection being adapted to vaporize at the throat of said venturi sectionat a predetermined temperature, means for sensing the pressure at saidthroat for generating a signal when the fluid vaporizes within saidthroat, and means including pressure responsive means for driving saidfirst fluid circulating means in response to the signal of saidlast-named means.

5. A heat exchanging system comprising a fluid circulating deviceadapted to circulate fluid in response to temperature variations, a heatexchanger, means for circulating a fluid through said heat exchanger,said means including a venturi section through which at least a portionof the fluid circulated flows, the fluid circulated through said venturisection and said heat exchanger being adapted to vaporize at the throatof said venturi section at a predetermined temperature, means forgenerating a signal when the fluid vaporizes within said throat, andmeans for driving said fluid circulating device in response to thesignal of said last-named means.

6. A heat exchanging system comprising a fluid circulating deviceadapted to circulate fluid in response to temperature variations, a heatexchanger, a pump for circulating a fluid, conduit means interconnectingsaid pump and said heat exchanger, a venturi section formed in a portionof said conduit means, the fluid circulated by said pump being adaptedto vaporize at the throat of said venturi section at a predeterminedtemperature, means for generating a signal when the fluid vaporizeswithin said throat, and means for driving said fluid circulating devicein response to the signal of said last-named means.

7. A heat exchanging system comprising a first pump adapted to circulatea fluid in response to temperature variations, a second pump forcirculating a fluid, a heat exchanger, conduit means interconnectingsaid pumps and said heat exchanger, a venturi section formed in aportion of said conduit means, the fluid circulated by said pumps beingadapted to vaporize at the throat of said venturi section at apredetermined temperature, means for generating a signal when the fluidvaporizes withm said throat, and means for driving said first pump inresponse to the signal of said last-named means.

8. A cooling system for a liquid cooled internal combustion enginecomprising a fluid circulating device adapted to be driven in responseto temperature variations, a cooling jacket for said engine, a coolantpump for circulating liquid coolant, a radiator for dlssipating the heatgenerated by said engine, conduit means interconnecting said coolantpump, said cooling jacket and said radiator, a venturi sectionpositioned in a portion of said conduit means, the liquid coolantflowing through said venturi section being adapted to vaporize at thethroat of said venturi section at a predetermined coolant temperature,means for generating a signal when the coolant vaporizes within saidthroat, and means for driving said fluid circulating device in responseto the signal of said last-named means.

9. A cooling system for a liquid cooled internal combustion enginecomprising a cooling jacket for said engine, a first coolant pump forcirculating a liquid coolant in response to temperature variations, asecond coolant pump driven by said engine for circulating a liquidcoolant during operation of said engine, a radiator for dissipating theheat generated by said engine, conduit means interconnecting saidcoolant pumps, said cooling jacket and said radiator, a venturi sectionpositioned in a portion of said conduit means, the liquid coolantflowing through said venturi section being adapted to vaporize at thethroat of said venturi section at a predetermined coolant temperature,means for generating a signal when the liquid coolant vaporizes withinsaid throat, and means for driving said first coolant pump in responseto the signal of said last-named means.

10. A heat exchanging system comprising a fluid circulating deviceadapted to be driven in response to temperature variations, a heatexchanger, means for circulat ing a fluid through said heat exchanger, aventuri section positioned to receive at least a portion of the fluidflowing through said heat exchanger, the fluid flowing through saidventuri section being adapted to vaporize at the throat of said venturisection at a predetermined temperature, means for sensing the pressuredifferential caused at said throat by the fluid vaporization, and meansincluding pressure responsive means for driving said fluid circulatingdevice in response to the sensing of a pressure variation by saidlast-named means.

11. A heat exchanging system comprising a fluid circulating deviceadapted to be driven in response to temperature variations, a heatexchanger, a pump for circulating a fluid, conduit means interconnectingsaid pump and said heat exchanger, a venturi section formed in a portionof said conduit means, the fluid circulated through said heat exchangerand said venturi section being adapted to vaporize at the throat of saidventuri section at a predetermined temperature, means for sensing thepressure differential caused at said throat by the fluid vaporization,and means including pressure responsive means for driving said fluidcirculating device in response to the sensing of a pressure variation bysaid last-named means.

12. A heat exchanging system comprising a first pump adapted tocirculate a fluid in response to temperature variations, a second pumpfor circulating the fluid, a heat exchanger, conduit meansinterconnecting said pumps and said heat exchanger, a venturi sect-ionformed in a portion of said conduit means, the fluid circulated by saidpumps being adapted to vaporize at the throat of said venturi section ata predetermined temperature, means for sensing the pressure difierentialcaused at said throat by the fluid vaporization, and means includingpressure responsive means for driving said first pump in response to thesensing of a pressure variation by said last-named means.

13. A cooling system for a liquid cooled internal combustion enginecomprising a fluid circulating device, a cooling jacket for said engine,a coolant pump for circulating a liquid coolant, a radiator fordissipating the heat generated by said engine, conduit meansinterconnecting said coolant pump, said cooling jacket and saidradiator, a venturi section positioned in a portion of said conduitmeans, the liquid coolant flowing through said venturi section beingadapted to vaporize at the throat of said venturi section at apredetermined coolant temperature, means for sensing the pressuredifferential caused at said throat by the coolant vaporization, andmeans including pressure responsive means for driving said fluidcirculating device in response to the sensing of a pressure variation bysaid last-named means.

14. A cooling system for a liquid cooled internal combustion enginecomprising a first coolant pump adapted to be driven by said engine inresponse to temperature variations, a second coolant pump drivencontinuously by said engine, a cooling jacket for said engine, aradiator for dissipating the heat generated by said engine, conduitmeans interconnecting said coolant pumps, said cooling jacket and saidradiator, a venturi section positioned in a portion of said conduitmeans, the liquid coolant flowing through said venturi section beingadapted to vaporize at the throat of said venturi section at apredetermined coolant temperature, means for sensing the pressuredifferential caused at said throat by the coolant vaporization, andmeans including pressure responsive means for coupling said firstcoolant pump to said engine in response to the sensing of a pressurevariation by said last-named means.

15. A cooling system for a liquid cooled internal combustion enginecomprising a cooling jacket for an internal combustion engine, a firstcoolant pump adapted to be driven intermediary by said engine, a secondcoolant pump adapted to be driven continuously by said engine, aradiator for dissipating the heat generated by said engine, conduitmeans interconnecting said coolant pumps, said cooling jacket and saidradiator, and temperature responsive clutch means for coupling saidfirst coolant pump to said engine when the coolant temperature exceeds apredetermined value.

16. A heat exchanging system comprising a pump, a driving member, a heatexchanger, conduit means interconnecting said pump with said heatexchanger, a venturi section, means for circulating a fluid through saidventuri section, a fluid pressure responsive clutch for drivinglycoupling said pump to said driving member comprising biasing means forurging said clutch to one of its engaged and disengaged positions, fluidpressure means opposing said biasing means and urging said clutch to itsother position, and conduit means interconnecting said fluid pressuremeans with said venturi section at its throat for transmitting thepressure at said throat to said fluid pressure means, the fluid flowingthrough said venturi section being adapted to vaporize at apredetermined temperature for decreasing the force exerted by said fluidpressure means whereby said biasing means may urge said clutch into thefirst of said positions.

17. A heat exchanging system comprising a first pump, a second pump, afluid pressure responsive clutch for drivingly coupling said first pumpto said driving member, means coupling said second pump to said drivingmemher, a heat exchanger, conduit means interconnecting said pumps withsaid heat exchanger, a venturi section positioned in a portion of saidconduit means, said fluid pressure responsive clutch comprising biasingmeans for urging said clutch to one of its engaged and disengagedpositions, fluid pressure means opposing said biasing means and urgingsaid clutch to the other of its positions, conduit means interconnectingsaid fluid pressure means with said venturi section at its throat fortransmitting the pressure at said throat to said fluid pressure means,the fluid flowing through said venturi section being adapted to vaporizeat a predetermined temperature for decreasing the force exerted by saidfluid pressure means whereby said biasing means may urge said clutchinto the first of said positions.

18. A cooling system for an internal combustion engine comprising afluid circulating device, a fluid pressure responsive clutch fordrivingly coupling said fluid circulating device to said engine, acoolant pump, means drivingly coupling said coolant pump to said engine,a radiator, a cooling jacket for said engine, conduit meansinterconnecting said coolant pump, said cooling jacket and saidradiator, a venturi section positioned in a portion of said conduitmeans, said fluid pressure responsive clutch comprising biasing meansfor urging said clutch to its engaged position, fluid pressure meansopposing said biasing means and urging said clutch to its disengagedposition, and conduit means interconnecting said fluid pressure meanswith said venturi section at its throat for transmitting the pressure atsaid throat to said fluid pressure means, the coolant flowing throughsaid venturi section being adapted to vaporize at a predetermined temperature for decreasing the force exerted by said fluid pressure meanswhereby said biasing means may urge said clutch into engagement to drivesaid fluid circulating device.

19. A cooling system for an internal combustion engine comprising acooling jacket, a first coolant pump, a fluid pressure responsive clutchfor drivingly coupling said first coolant pump to said engine, a secondcoolant pump, means drivingly coupling said second coolant pump to saidengine, a radiator for dissipating the heat generated by said engine,conduit means interconnecting said coolant pumps, said cooling jacketand said radiator, a venturi section positioned in a portion of saidconduit means, said fluid pressure responsive clutch comprising biasingmeans for urging said clutch into its engaged position, fluid pressuremeans opposing said biasing means and urging said clutch into itsdisengaged position, and conduit means interconnecting said fluidpressure means with said venturi section at its throat for transmittingthe pressure at said throat to said fluid pressure means, the coolantflowing through said venturi section being adapted to vaporize at apredetermined temperature for decreasing the force exerted by said fluidpressure means whereby said biasing means may urge said clutch into itsengaged position for drivingly coupling said first coolant pump to saidengine.

20. A temperature responsive fluid pump comprising a first impeller, asecond impeller concentrically disposed with respect to said firstimpeller and axially aligned therewith, a driving shaft, means foraffixing one of said impellers to said driving shaft, fluid pressureresponsive clutch means for drivingly coupling the other of saidimpellers of said driving shaft, said fluid pressure responsive clutchmeans comprising biasing means for urging said clutch means to one ofits engaged and disengaged positions and fluid pressure means for urgingsaid clutch to the other of said positions, a venturi section adapted toreceive a portion of the fluid circulated by said impellers, and meansfor transmitting the pressure at the throat of said venturi section tosaid pressure responsive means.

No references cited.

KARL J. ALBRECHT, Primary Examiner.

1. TEMPERATURE RESPONSIVE MEANS FOR ACTUATING A FLUID CIRCULATING MEANSCOMPRISING A VENTURI SECTION, MEANS FOR CIRCULATING A FLUID THROUGH SAIDVENTURI SECTION, THE FLUID CIRCULATED THROUGH SAID VENTURI SECTION BEINGADAPTED TO VAPORIZE AT THE THROAT OF SAID VENTURI SECTION AT APREDETERMINED TEMPERATURE, MEANS FOR GENERATING A SIGNAL WHEN THE FLUIDVAPORIZES WITHIN SAID THROAT, AND MEANS FOR DRIVING SAID FLUIDCIRCULATING MEANS IN RESPONSE TO THE SIGNAL OF SAID LAST-NAMED MEANS.